Field of the Invention
This invention relates to a magnetic recording media. More particularly this invention relates to a magnetic recording media with excellent surface and desirable electromagnetic properties, obtained by preparing a radiation-sensitive curing resin by modification of a four-component copolymer containing vinyl chloride, a vinyl carboxylate, an unsaturated carboxylic acid and an unsaturated carboxylic anhydride; blending the resin with another polymer and a magnetic powder thereby producing a magnetic paint; applying the magnetic paint as a coating to a non-magnetic substrate; and solidifying the applied coating of paint with radiation.
Today, magnetic recording media have found extensive utility in various forms such as magnetic tapes for use in audio devices and video devices, magnetic disks for use in electronic computers and word processors, and magnetic cards for various household applications. Heretofore in the production of such a magnetic recording media, it has been customary to use a radiation-sensitive curing resin as a binder for a formulation containing magnetic powder, deposit the resultant magnetic paint on a substrate, and expose the applied coating of the paint on the substrate to radiation to cross link and polymerize the coating.
A magnetic redcording medium using the aforementioned radiation-sensitive curing resin as the binder, however, suffers from the disadvantage that it has a high frictional coefficient and is deficient in surface properties such as gloss, capacity for orientation and electromagnetic property. For the purpose of eliminating this disadvantage, the inventors have already developed a resin solution for magnetic paint using as a main component therefor a copolymer, 100 to 400 in average polymerization degree, which is a four-component copolymer of (A) vinyl chloride, (b) a vinyl carboxylate, (C) an unsaturated carboxylic acid and (D) an unsaturated carboxylic anhydride, containing 50 to 80% by weight of (A) based on the total of (A) and (B), 10 to 30% by weight of (D) based on the total of (C) and (D) and a total of 1 t 5 parts by weight of (C) and (D) based on 100 parts by weight of (A) and (B) (Japanese Patent Laid Open No. SHO 57(1982)-128,711). A magnetic recording medium produced by using this resin solution, however, is still deficient in frictional coefficient, gloss, capacity for orientation and electromagnetic property.
An object of this invention, therefore, is to provide an improved magnetic recording medium. Another object of this invention is to provide a magnetic recording medium which has a low frictional coefficient and excels in surface property, capacity for orientation, and electromagnetic property.